With the advantages of high image quality, small volume, light weight, low driving voltage and low power consumption, the liquid crystal display devices have been widely used in various IT digital products, such as car navigation systems, engineering workstations, monitors, portable information terminals, electronic terminals, electronic books, laptops, and large-sized direct-viewing televisions of flat panel.
The traditional liquid crystal display panel mainly comprises a thin film transistor array substrate, a color filter substrate, and a liquid crystal layer that is arranged between the above two substrates. However, the resolution of this kind of display panel is poor, and the aperture ratio thereof is low. Moreover, a positioning error would occur when the color filter substrate is aligned with the thin film transistor array substrate.
In recent years, the technology that the color filter layer is integrated directly into the thin film transistor array substrate (Color Filter on Array, i.e., COA) has been developed. As shown in FIG. 1, the liquid crystal display panel that is produced through the COA technology mainly comprises a COA substrate 101, an opposite substrate 102, and a liquid crystal layer 103 arranged therebetween. The COA substrate 101 comprises a glass substrate 104, a silicon nitride insulation layer 105, a capacitor electrode 106, a first silicon nitride passivation protection layer 107, a color filter layer 108, a second silicon nitride passivation protection layer 109, and a pixel electrode 110. Since the color filter layer 108 is integrated into the COA substrate 101, the opposite substrate 102 comprises no color filter layer. In the COA technology, the color filter layer is directly formed on the thin film transistor array substrate, and therefore, the positioning error, which would otherwise be caused when the color filter substrate is aligned with the thin film transistor array substrate of the traditional liquid crystal display panel, would not occur. Moreover, the resolution and the aperture ratio of the liquid crystal display panel can both be improved through COA technology.
In the COA substrate, the color filter layer 108 is arranged between the capacitor electrode 106 and the pixel electrode 110. However, since the dielectric constant of the color filter layer would change with temperature, a capacitance of a storage capacitor that is formed by a storage electrode and a pixel electrode is not stable. Consequently, during the manufacturing of the COA substrate, the capacitance of the storage capacitor cannot meet the requirement thereof. Therefore, a device through which the capacitance of the storage capacitor of the array substrate can be obtained during manufacturing process is needed.